Practical guide
Understanding retirement income gap — target other monthly retirement income
Everyday editorial team · GEOINNOVATION CO., LTD · Published · Updated
What this calculation is for
A retirement-income gap compares a desired spending amount with other income and an illustrative portfolio draw. It makes an unfunded goal visible without assuming that an income target automatically changes the savings projection.
How the method works
Savings grow from the entered balance and deposits until retirement. A withdrawal assumption converts the projected fund to monthly income, which is combined with entered benefits and compared with the target. The displayed model uses: Project savings and estimated monthly withdrawal income; compare with target after entered other income.
A worked example
For an illustrative retirement income gap scenario, use Desired monthly retirement income: 6500 $; Other monthly retirement income: 2200 $; Current retirement savings: 400000 $; Years until retirement: 15 years; Monthly savings until retirement: 800 $; Assumed annual return: 5 %; Initial withdrawal rate: 4 %. The modeled estimated monthly retirement income is $5,678.1. These are example assumptions, not current prices, official benefit amounts or personalized advice.
Assumptions and real-world differences
Benefit estimates, taxation, inflation and a sustainable withdrawal policy require separate review. The result is not a Social Security benefit calculation or a probability that the plan will succeed. Social Security or pension amounts are user estimates; taxes and benefit eligibility are excluded.
Solving for other monthly retirement income
This reverse calculation searches for a other monthly retirement income that makes the model’s headline measure approach your target. Set a lower and upper search bound, leave the other assumptions consistent, and inspect the achieved result and target difference. The returned number is an input, not the original model’s output. A bounded solution can be approximate when the allowed input step rounds values.
Reproduce this tool’s example
These fixed example inputs are independent of edits you make above. Enter them in this tool to reproduce the result, then replace them with your own assumptions.
- Target: estimated monthly retirement income
- 5,678.1 $
- Minimum other monthly retirement income
- 1,100 $
- Maximum other monthly retirement income
- 3,300 $
- Desired monthly retirement income
- 6,500 $
- Current retirement savings
- 400,000 $
- Years until retirement
- 15 years
- Monthly savings until retirement
- 800 $
- Assumed annual return
- 5 %
- Initial withdrawal rate
- 4 %
Required other monthly retirement income: $2,200
Closest modeled result: $5,678.1.
- Target headline value: 5,678.1
- Calculated headline value: $5,678.1
- Absolute target difference: 0
Frequently asked questions
- Should benefits and the target use the same dollar basis?
- Yes. Avoid comparing a today’s-dollar spending target with unadjusted future-dollar benefits or balances.
- Which inputs should I check before using this retirement income gap estimate?
- Check desired monthly retirement income, other monthly retirement income, current retirement savings, years until retirement, monthly savings until retirement, assumed annual return, initial withdrawal rate. Match each field’s unit and time period, then compare the detailed rows rather than treating the headline alone as the complete answer.
- Why might there be no exact required other monthly retirement income?
- The target may be outside the search range. Rounded outputs, whole-item counts, tax thresholds and flat responses can also prevent an exact solution. Bisection requires a monotonic response within the chosen range; do not interpret a failed search as a real-world impossibility.